Check out this Thread. I had a look on the IMS web site and the list the same pegs for the 90-96 WR250 as the 90-96 YZ250. I think they will fit.
Check this Ebay link out. Or search Ebay for YZ250 foot pegs and look for anything that fits 90-96 YZ250. The IMS foot pegs are made from stainless steel and are very good quality.